Monday, October 18, 2010

Codominance - Roan Cows and Erminette Chickens

In some traits, there are dominant alleles that fight for expression.  Because they are both dominant, neither one wants to give up expression -- there will be NO blending of phenotype here.

Here are some classic examples!

ROAN COWS

These cows have possibilites of several colors of hairs that aren't a blend of the dominant and recessive phenotypes because the traits for each phenotype are dominant. 
http://en.wikipedia.org/wiki/Roan_(color)#Roan_cattle
RR = red cow hairs
RW = red and white cow hairs
WW = white cow hairs



http://myloupe.com/home/info-price-rf.php?image_id=465633
ERMINETTE CHICKENS

These chickens have feathers that are both white and black, but not grey.

BB = black feathers
BW = black and white feathers
WW = white feathers


http://sydfish.wordpress.com/2008/02/25/give-blood/
BLOOD TYPE

The alleles for A and B are codominant so that if both are in the genetic code then they are expressed as blood type AB.







1 comment:

  1. I wasn't looking for genes! I googled 'black & white checkered chickens' to find out what they were called, and well, i did! Thabks!

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